Solid state transducers with state detection, and associated systems and methods

ABSTRACT

Solid state transducers with state detection, and associated systems and methods are disclosed. A solid state transducer system in accordance with a particular embodiment includes a support substrate and a solid state emitter carried by the support substrate. The solid state emitter can include a first semiconductor component, a second semiconductor component, and an active region between the first and second semiconductor components. The system can further include a state device carried by the support substrate and positioned to detect a state of the solid state emitter and/or an electrical path of which the solid state emitter forms a part. The state device can be formed from at least one state-sensing component having a composition different than that of the first semiconductor component, the second semiconductor component, and the active region. The state device and the solid state emitter can be stacked along a common axis. In further particular embodiments, the state-sensing component can include an electrostatic discharge protection device, a thermal sensor, or a photosensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/223,136, filed Aug. 31, 2011, now U.S. Pat. No. 9,490,239, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present technology is directed generally to solid state transducers(“SSTs” including transducers having integrated state detection devicesand functions, and associated systems and methods.

BACKGROUND

Solid state lighting (“SSL”) devices are used in a wide variety ofproducts and applications. For example, mobile phones, personal digitalassistants (“PDAs”), digital cameras, MP3 players, and other portableelectronic devices utilize SSL devices for backlighting. SSL devices arealso used for signage, indoor lighting, outdoor lighting, and othertypes of general illumination. SSL devices generally use light emittingdiodes (“LEDs”), organic light emitting diodes (“OLEDs”), and/or polymerlight emitting diodes (“PLEDs”) as sources of illumination, rather thanelectrical filaments, plasma, or gas. FIG. 1A is a cross-sectional viewof a conventional SSL device 10 a with lateral contacts. As shown inFIG. 1A, the SSL device 10 a includes a substrate 20 carrying an LEDstructure 11 having an active region 14, e.g., containing galliumnitride/indium gallium nitride (GaN/InGaN) multiple quantum wells(“MQWs”), positioned between N-type GaN 15 and P-type GaN 16. The SSLdevice 10 a also includes a first contact 17 on the P-type GaN 16 and asecond contact 19 on the N-type GaN 15. The first contact 17 typicallyincludes a transparent and conductive material (e.g., indium tin oxide(“ITO”)) to allow light to escape from the LED structure 11. Inoperation, electrical power is provided to the SSL device 10 a via thecontacts 17, 19, causing the active region 14 to emit light.

FIG. 1B is a cross-sectional view of another conventional LED device 10b in which the first and second contacts 17 and 19 are opposite eachother, e.g., in a vertical rather than lateral configuration. Duringformation of the LED device 10 b, a growth substrate, similar to thesubstrate 20 shown in FIG. 1A, initially carries an N-type GaN 15, anactive region 14 and a P-type GaN 16. The first contact 17 is disposedon the P-type GaN 16, and a carrier 21 is attached to the first contact17. The substrate is removed, allowing the second contact 19 to bedisposed on the N-type GaN 15. The structure is then inverted to producethe orientation shown in FIG. 1B. In the LED device 10 b, the firstcontact 17 typically includes a reflective and conductive material(e.g., silver or aluminum) to direct light toward the N-type GaN 15.

One aspect of the LEDs shown in FIGS. 1A and 1B is that an electrostaticdischarge (“ESD”) event can cause catastrophic damage to the LED, andrender the LED inoperable. Accordingly, it is desirable to reduce theeffects of ESD events. However, conventional approaches for mitigatingthe effects of ESD typically include connecting a protection diode tothe SST device, which requires additional connection steps and cancompromise the electrical integrity of the resulting structure. Anotheraspect of the LEDs shown in FIGS. 1A and 1B is that the performancelevels of the devices may vary due to internal heating, drive current,device age and/or environmental effects. Accordingly, there remains aneed for reliably and cost-effectively manufacturing LEDs with suitableprotection against ESD and other performance-degrading factors.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views and/or embodiments.

FIG. 1A is a partially schematic, cross-sectional illustration of an SSLdevice having a lateral arrangement in accordance with the prior art.

FIG. 1B is a partially schematic, cross-sectional illustration ofanother SSL device having a vertical arrangement in accordance with theprior art.

FIG. 2A is a schematic block diagram of a system configured inaccordance with an embodiment of the presently disclosed technology.

FIG. 2B is a cross-sectional view of an SST device having anelectrostatic discharge device, configured and integrated in accordancewith embodiments of the presently disclosed technology.

FIGS. 3A-3G are cross-sectional views of a portion of a microelectronicsubstrate undergoing a process for forming an SST device and anassociated electrostatic discharge device in accordance with embodimentsof the presently disclosed technology.

FIG. 4 is a cross-sectional view of an SST device having anelectrostatic discharge device configured and integrated in accordancewith embodiments of the presently disclosed technology.

FIGS. 5A and 5B are cross-sectional views of the SST device of FIG. 4during operation in accordance with embodiments of the presentlydisclosed technology.

FIG. 6 is a partially schematic illustration of an SST device having anintegrated photodiode formed from an epitaxial growth substrate inaccordance with an embodiment of the presently disclosed technology.

FIG. 7 is a partially schematic, cross-sectional illustration of an SSTdevice having an integrated photodiode formed on an additional substratematerial in accordance with another embodiment of the presentlydisclosed technology.

FIGS. 8A-8L are partially schematic, cross-sectional illustrations of aprocess for forming an SST device having an integrated photodiodelocated beneath an active material in accordance with another embodimentof the presently disclosed technology.

FIG. 9 is a partially schematic, isometric illustration of an SST devicehaving an integrated thermal sensor in accordance with still anotherembodiment of the presently disclosed disclosure.

DETAILED DESCRIPTION

Specific details of several embodiments of representative SST devicesand associated methods of manufacturing SST devices are described below.The term “SST” generally refers to solid-state transducer devices thatinclude a semiconductor material as the active medium to convertelectrical energy into electromagnetic radiation in the visible,ultraviolet, infrared, and/or other spectra. For example, SSTs includesolid-state light emitters (e.g., LEDs, laser diodes, etc.) and/or othersources of emission other than electrical filaments, plasmas, or gases.In other embodiments, SSTs can include solid-state devices that convertelectromagnetic radiation into electricity. The term solid state emitter(“SSE”) generally refers to the solid state components or light emittingstructures that convert electrical energy into electromagnetic radiationin the visible, ultraviolet, infrared, and/or other spectra. SSEsinclude semiconductor LEDs, PLEDs, OLEDs, and/or other types of solidstate devices that convert electrical energy into electromagneticradiation in a desired spectrum. A person skilled in the relevant artwill understand that the new, presently disclosed technology may haveadditional embodiments and that this technology may be practiced withoutseveral of the details of the embodiments described below with referenceto FIGS. 2A-9.

Reference herein to “one embodiment”, “an embodiment”, or similarformulations, means that a particular feature, structure, operation, orcharacteristic described in connection with the embodiment, is includedin at least one embodiment of the present technology. Thus, theappearances of such phrases or formulations herein are not necessarilyall referring to the same embodiment. Furthermore, various particularfeatures, structures, operations, or characteristics may be combined inany suitable manner in one or more embodiments.

In particular embodiments, a solid state transducer system includes asupport substrate and a solid state emitter carried by the supportsubstrate. The solid state emitter can comprise a first semiconductorcomponent, a second semiconductor component, and an active regionbetween first and second semiconductor components. The system furtherincludes a state device carried by the support substrate and positionedto detect a state of the solid state emitter and/or an electrical pathof which the solid state emitter forms a part. The state device isformed from at least one state-sensing component having a compositiondifferent than that of the first semiconductor component, the secondsemiconductor component, and the active region. The state device and thesolid state emitter can be stacked along a common axis. For example, inparticular embodiments, the state device can include an electrostaticdischarge protection device, a photosensor, or a thermal sensor. Thestate device can be formed integrally with the solid state emitter,using (in at least some embodiments) a portion of the same epitaxialgrowth substrate used to form the SSE. The state device can be formedabove or below the stacking axis of the solid state emitter, directlyalong the axis, or off the axis, depending upon the particularembodiment.

FIG. 2A is a schematic illustration of a representative system 290. Thesystem 290 can include an SST device 200, a power source 291, a driver292, a processor 293, and/or other subsystems or components 294. Theresulting system 290 can perform any of a wide variety of functions,such as backlighting, general illumination, power generation, sensing,and/or other functions. Accordingly, representative systems 290 caninclude, without limitation, hand-held devices (e.g., cellular or mobilephones, tablets, digital readers, and digital audio players), lasers,photovoltaic cells, remote controls, computers, lights and lightingsystems, and appliances (e.g., refrigerators, for example). Componentsof the system 290 may be housed in a single unit or distributed overmultiple, interconnected units (e.g., through a communications network).The components of the system 290 can also include local and/or remotememory storage devices, and any of a wide variety of computer-readablemedia.

In many instances, it is desirable to monitor the performance of the SSTdevice 200 and/or the environment in which the SST device 200 operates,and make appropriate adjustments. For example, if the SST device 200 issubjected to an excessive voltage (e.g., an electrostatic discharge or“ESD”), it is desirable to protect the device with a diode or othernon-linear circuit component. If the SST device 200 approaches anoverheat condition, it may be desirable to reduce the current suppliedto the device until the device cools down. If the SST device 200includes a solid state lighting (SSL) device, and the light emitted bythe device does not meet target emission specifications, it may bedesirable to adjust the output of the device. In each of theserepresentative examples, the system 290 can includes a state monitor ordevice 295 that monitors a state of the SST device 200, and participatesin or facilitates a response. In some cases the state monitor 295 canact directly to provide a response. For example, a diode wired inparallel with the SST device 200 can respond directly to a high voltageby closing, causing the current to bypass the SST device 200. In otherembodiments, the state monitor 295 can respond with the assistance ofanother device, e.g., the processor 293. For example, if the statemonitor 295 is a photosensor, it can provide a signal to the processor293 corresponding to a warmth, color and/or other characteristic of theemitted light, and the processor 293 can issue a responsive command tochange the output of the SSE. In another embodiment, the state monitor295 includes a thermistor, and can provide to the processor 293 a signalcorresponding to a high temperature condition. The processor 293 canrespond by directing the SST device 200 to reduce power or ceaseoperation until the temperature falls, in order to reduce the impact ofthe elevated temperature on the SST device 200.

Specific examples of state monitors that include ESD protection devicesare described below with reference to FIGS. 2B-5B. Certain features ofthese examples are also described in co-pending U.S. application Ser.No. 13/223,098 titled “Solid State Lighting Devices, Including DevicesHaving Integrated Electrostatic Discharge Protection, and AssociatedSystems and Methods,” filed on Aug. 31, 2011, and incorporated herein byreference. Examples of state monitors that include photosensors aredescribed below with reference to FIGS. 6-8L, and examples of statemonitors that include thermal sensors (e.g., thermistors) are describedbelow with reference to FIG. 9. In any of these embodiments, the statemonitor can detect the state of the SSE (e.g., as is the case with aphotosensor and a thermal sensor) and/or the state of an electrical pathor circuit of which the SSE forms or part (as is the case with an ESDdiode).

FIG. 2B is a cross-sectional view of an SST device 200 configured inaccordance with embodiments of the presently disclosed technology. TheSST device 200 can include an SSE 202 mounted to or otherwise carried bya support substrate 230. The SST device 200 further includes a statedevice or monitor 295 in the form of an electrostatic discharge device250 carried by the SSE 202. Accordingly, the electrostatic dischargedevice 250 represents a specific example of a state monitor. As will bedescribed further below, the electrostatic discharge device 250 can bemanufactured to be integral with the SST device 200 (and in particular,the SSE 202) e.g., to improve system reliability, manufacturabilityand/or performance, and/or to reduce system size.

The SSE 202 can include a first semiconductor material 204, a secondsemiconductor material 208, and an active region 206 between the firstand second semiconductor materials 204, 208. In one embodiment, thefirst semiconductor material 204 is a P-type gallium nitride (“GaN”)material, the active region 206 is an indium gallium nitride (“InGaN”)material, and the second semiconductor material 208 is an N-type GaNmaterial. In other embodiments, the semiconductor materials of the SSE202 can include at least one of gallium arsenide (“GaAs”), aluminumgallium arsenide (“AlGaAs”), gallium arsenide phosphide (“GaAsP”),aluminum gallium indium phosphide (AlGaInP), gallium(III) phosphide(“GaP”), zinc selenide (“ZnSe”), boron nitride (“BN”), aluminum nitride(“AlN”), aluminum gallium nitride (“AlGaN”), aluminum gallium indiumnitride (“AlGaInN”), and/or another suitable semiconductor material.

The illustrated electrostatic discharge device 250 includes an epitaxialgrowth substrate 210 and a semiconductor material 216 (e.g., a buffermaterial). The electrostatic discharge device 250 further includes afirst contact 246 (e.g., formed from a first conductive material)electrically connected to a via 240 that extends through theelectrostatic discharge device 250 and through a portion of the SSE 202.The first contact 246 electrically contacts a conductive (and typicallyreflective) material 220 below the active region 206 and can provide anexternal terminal for interfacing with a power source or sink.Accordingly, the conductive material 220 operates as a P-contact. Thefirst contact 246 is electrically insulated in the via 240 from thesurrounding semiconductor material 216 and portions of the SSE 202 by aninsulator 242. The illustrated electrostatic discharge device 250further includes a second contact 248 (e.g., formed from a secondconductive material) that doubles as an N-contact for the SSE 202.Accordingly, the second contact 248 can extend over an upper surface 209of the SSE 202 e.g., in contact with the N-type material 208. The secondcontact 248 is electrically insulated from the semiconductor material216 by a second insulator 244, and is transparent to allow radiation(e.g., visible light) to pass out through the external surface of theSST device 200 from the active region 206. In the illustratedembodiment, the first contact 246 and the second contact 248 are sharedby the SSE 202 and the electrostatic discharge device 250. Morespecifically, the first contact 246 is electrically coupled to both thefirst semiconductor layer 204 of the SSE 202 and the epitaxial growthsubstrate 210 of the electrostatic discharge device 250. The secondcontact 248 is electrically coupled to both the second semiconductorlayer 208 of the SSE 202 and the epitaxial growth substrate 210 of theelectrostatic discharge device 250. Accordingly, the electrostaticdischarge device 250 is connected in parallel with the SSE 202. Theconductive materials forming the first contact 246, the second contact248 and an electrical path though the via 240 can be the same ordifferent, depending upon the particular embodiment. For example, thevia 240 can include a third conductive material that is the same as thefirst conductive material, though it may be deposited in a separatestep.

The SST device 200 can be coupled to a power source 270 that is in turncoupled to a controller 280. The power source 270 provides electricalcurrent to the SST device 200, under the direction of the controller280. During normal operation, as current flows from the firstsemiconductor material 204 to the second semiconductor material 208,charge-carriers flow from the second semiconductor material 208 towardthe first semiconductor material 204 and cause the active region 206 toemit radiation. The radiation is reflected outwardly by the conductive,reflective material 220. The electrostatic discharge device 250 providesa bypass path for current to flow between the first contact 246 and thesecond contact 248 under high (e.g., excessive) voltage conditions. Inparticular, the epitaxial growth substrate 210 between the first contact246 and the second contact 248 can form a diode in parallel with the SSE202, but with the opposite polarity. During normal operating conditions,the bias of the epitaxial growth substrate 210 prevents current flowthrough it from the first contact 246 to the second contact 248, forcingthe current to pass through the SSE 202. If a significant reversevoltage is placed across the contacts 246, 248, (e.g., during anelectrostatic discharge event), the epitaxial growth substrate 210becomes highly conductive in the reverse direction, allowing the reversecurrent to flow through it, thus protecting the SST device from thereverse current flow.

The present technology further includes methods of manufacturing SSTdevices. For example, one method of forming a SST device can includeforming an SSE and an electrostatic discharge device from a commonepitaxial growth substrate. Representative steps for such a process aredescribed in further detail below with reference to FIGS. 3A-3G.

FIGS. 3A-3G are partially schematic, cross-sectional views of a portionof a microelectronic substrate 300 undergoing a process of forming anembodiment of the SST device 200 described above, in accordance withembodiments of the technology. FIG. 3A shows the substrate 300 after asemiconductor material 216 (e.g., a buffer material) has been disposedon the epitaxial growth substrate 210. The epitaxial growth substrate210 can be silicon (e.g., Si (1,0,0) or Si (1,1,1)), GaAs, siliconcarbide (SiC), polyaluminum nitride (“pAlN”), engineered substrates withsilicon epitaxial surfaces (e.g., silicon on polyaluminum nitride),and/or other suitable materials. The semiconductor material 216 can bethe same material as the epitaxial growth substrate 210 or a separatematerial bonded to the epitaxial growth substrate 210. For example, theepitaxial growth substrate 210 can be pAlN and the semiconductormaterial 216 can be Si (1,1,1). In any of these embodiments, the SSE 202is formed on the semiconductor material 216.

The SSE 202 includes the first semiconductor material 204, the activeregion 206, and the second semiconductor material 208, which can besequentially deposited or otherwise formed using chemical vapordeposition (“CVD”), physical vapor deposition (“PVD”), atomic layerdeposition (“ALD”), plating, or other techniques known in thesemiconductor fabrication arts. In the embodiment shown in FIG. 3A, thesecond semiconductor material 208 is grown or formed on thesemiconductor material 216, the active region 206 is grown or formed onthe second semiconductor material 208, and the first semiconductormaterial 204 is grown or formed on the active region 206. In oneembodiment, N-type GaN (as described above with reference to FIG. 2B) ispositioned proximate to the epitaxial growth substrate 210, but in otherembodiments P-type GaN is positioned proximate to the epitaxial growthsubstrate 210. In any of these embodiments, the SSE 202 can includeadditional buffer materials, stress control materials, and/or othermaterials, and/or the materials can have other arrangements known in theart.

In the embodiment shown in FIG. 3A, a conductive, reflective material220 a is formed over the first semiconductor material 204. Theconductive, reflective material 220 a can be silver (Ag), gold (Au),gold-tin (AuSn), silver-tin (AgSn), copper (Cu), aluminum (Al), or anyother suitable material that can provide electrical contact and reflectlight emitted from the active region 206 back through the firstsemiconductor material 204, the active region 206, and the secondsemiconductor material 208, as described above with reference to FIG.2B. The conductive, reflective material 220 a can be selected based onits thermal conductivity, electrical conductivity, and/or the color oflight it reflects. For example, silver generally does not alter thecolor of the reflected light. Gold, copper, or other colored reflectivematerials can affect the color of the light and can accordingly beselected to produce a desired color for the light emitted by the SSE202. The conductive, reflective material 220 a can be deposited directlyon the first semiconductor material 204, or a transparent electricallyconductive material 221 (shown in broken lines) can be disposed betweenthe first semiconductor material 204 and the reflective material 220 a.The transparent electrically-conductive material 221 can be indium tinoxide (ITO) or any other suitable material that is transparent,electrically conductive, and adheres or bonds the reflective material220 a to the first semiconductor material 204. The transparent,electrically conductive material 221 and the reflective material 220 acan be deposited using CVD, PVD, ALD, plating, or other techniques knownin the semiconductor fabrication arts. The transparent, electricallyconductive material 221 and/or the reflective material 220 a canaccordingly form a conductive structure 222 adjacent to (e.g., incontact with) the SSE 202.

FIG. 3B illustrates an embodiment of a support substrate 230 beingbonded or otherwise attached to the SSE 202. The support substrate 230can include an optional backside reflective material 220 b. The backsidereflective material 220 b is bonded or otherwise attached to thereflective material 220 a using an elevated pressure and/or elevatedtemperature process.

FIG. 3C shows an embodiment in which the bonded reflective materials 220a, 220 b (FIG. 3B) form a combined reflective material 220. Theepitaxial growth substrate 210 has also been thinned, e.g., bybackgrinding. At this point, the remaining epitaxial growth substrate210 can be implanted with a p-type dopant (e.g., boron) to form a p-njunction with the underlying silicon or other semiconductor material216. In another embodiment, the substrate 210 can be doped in a priorstep. In either embodiment, because the semiconductor material 216typically includes buffer layers to facilitate forming the SSE 202, andbecause the buffer layers typically include undoped, large-bandgapsemiconductor layers (e.g., GaN, AlGaN or AlN), the p-n junction will beelectrically isolated from the epitaxial junction that forms the SSE202.

FIG. 3D illustrates the microelectronic substrate 300 after (a) theepitaxial growth substrate 210 has been background and/or etched, (b)the substrate 300 has been inverted, and (c) the epitaxial growthsubstrate 210 has been doped. Most of the semiconductor material 216 andthe epitaxial growth substrate 210 has been removed using grinding,etching, and/or other processes to expose an outer surface 209 of thesecond semiconductor material 208 or other portions of the SSE 202. Aportion of the semiconductor material 216 and the epitaxial growthsubstrate 210 remain on the SSE 202 to form the electrostatic dischargedevice 250. This is one manner in which the electrostatic dischargedevice 250 can be made integral with the SSE 202 and the SST 300. Infurther embodiments, the same or similar techniques can be used to formmultiple electrostatic discharge devices 250 integral with the SSE 202e.g., after the surface 209 has been selectively etched or otherwisetreated.

FIG. 3E illustrates the microelectronic substrate 300 after a via 240has been formed through the electrostatic discharge device 250 and aportion the SSE 202. The via 240 can be formed by drilling, etching, orother techniques known in the semiconductor fabrication arts. The via240 includes sidewalls 241 and provides access to the reflectivematerial 220 which is in electrical communication with the firstsemiconductor material 204. In other embodiments, the via 240 providesaccess to the conductive material 221, which is in direct electricalcontact with the first semiconductor material 204. FIG. 3F shows themicroelectronic substrate 300 after a first insulator 242 has beendeposited or formed in the via 240 and a second insulator 244 has beendeposited or formed on a lateral sidewall 243 of the electrostaticdischarge device 250.

FIG. 3G shows the microelectronic substrate 300 after a conductivematerial has been disposed in the via 240 (inward of the first insulator242), and outside the via 240 to form the first contact 246. The firstcontact 246 can comprise silver (Ag), gold (Au), gold-tin (AuSn),silver-tin (AgSn), copper (Cu), aluminum (Al), and/or other conductivematerials. The first contact 246 is insulated from the semiconductormaterial 216 and the SSE 202 by the first insulator 242. The secondcontact 248 has been deposited or otherwise disposed or formed on theouter surface 209 of the SSE 202 and on the epitaxial growth substrate210 of the electrostatic discharge device 250. The second insulator 244insulates the second contact 248 from the semiconductor material 216.

In selected embodiments, a lens (not shown in FIG. 3G) can be formedover the SSE 202. The lens can include a light-transmissive materialmade from silicone, polymethylmethacrylate (PMMA), resin, or othermaterials with suitable properties for transmitting the radiationemitted by the SSE 202. The lens can be positioned over the SSE 202 suchthat light emitted by the SSE 202 and reflected by the reflectivematerial 220 passes through the lens. The lens can include variousoptical features, such as a curved shape, to diffract or otherwisechange the direction of light emitted by the SSE 202 as it exits thelens.

Embodiments of the integral electrostatic discharge device 250 offerseveral advantages over traditional systems. For example, because inparticular embodiments the electrostatic discharge device 250 iscomprised of materials (e.g., the epitaxial growth substrate 210 and thesemiconductor material 216) that are also used to form the SSE 202, thematerial cost can be less than that of separately-formed electrostaticdevices. Moreover, traditional systems having a separate electrostaticdischarge die require additional pick-and-place steps to place the dieproximate to the SSE 202. Still further, such traditional systemsrequire forming additional and/or separate electrical connections toconnect the electrostatic device to the SSE.

FIG. 4 is a cross-sectional view of an SST device 400 having anelectrostatic discharge device 450 configured in accordance with furtherembodiments of the present technology. The SST device 400 can haveseveral features generally similar to those described above withreference to FIGS. 2-3G. For example, the SST device 400 can include anSSE 202 that in turn includes a first semiconductor material 204 (e.g.,a P-type material), a second semiconductor material 208 (e.g., an N-typematerial), and an active region 206 between the first and secondsemiconductor materials 204, 208. The SST device 400 can further includea reflective material 220 between the support substrate 230 and the SSE202. Typically, the SSE 202 and the reflective/conductive material 220are formed on an epitaxial growth substrate 210 (shown in dashed linesin FIG. 4). The structures that form the electrostatic discharge device450 and that electrically connect the electrostatic discharge device 450to the SSE can be formed on the SSE 202 while the SSE 202 is supportedby the epitaxial growth substrate 210. The epitaxial growth substrate210 can then be removed.

In the illustrated embodiment, the electrostatic discharge device 450 isfabricated on the SSE 202, and both the SSE 202 and the electrostaticdischarge device 450 are carried by the substrate 230, with theelectrostatic discharge device 450 positioned between the substrate 230and the SSE 202. Typically, the fabrication steps for forming theelectrostatic discharge device 450 are performed while the SSE 202 isinverted from the orientation shown in FIG. 4, and before the substrate230 is attached. The electrostatic discharge device 450 can include aplurality of electrostatic junctions 460 (identified individually asfirst-third junctions 460 a-460 c). Each electrostatic junction 460 caninclude a first conductive material 454 (identified individually byreference numbers 454 a-454 c), an intermediate material 456 (identifiedindividually by reference numbers 456 a-456 c), and a second conductivematerial 458 (identified individually by reference numbers 458 a-458 c).The materials can be disposed using any of a variety of suitabledeposition, masking, and/or etching processes. These materials can bedifferent than the materials forming the SSE 202 because they are notrequired to perform a light emitting function. As noted above and aswill be understood by one of ordinary skill in the art, these techniquescan be used to sequentially form the illustrated layers on the SSE 202while the SST 400 is inverted relative to the orientation shown in FIG.4. One or more insulating materials 461 electrically isolates the layersfrom the first semiconductor material 204 and/or from the supportsubstrate 230.

The intermediate material 456 can have electrical properties differentthan those of the first conductive material 454 and the secondconductive material 458. In some embodiments, the intermediate material456 can be a semiconductor (e.g., amorphous silicon) or a metal. Thefirst conductive material 454 a of one junction (e.g., the firstjunction 460 a) is electrically coupled to the second conductivematerial 458 b of an adjacent junction (e.g., the second junction 460b). While the illustrated electrostatic discharge device 450 includesthree junctions 460 placed in series, in further embodiments more orfewer junctions 460 can be used. Furthermore, to obtain differentcurrent-handling capacities for the electrostatic discharge device 450,the junctions 460 can be altered in size, and/or multiple junctions 460can be arranged in parallel.

The electrostatic discharge device 450 can further include a firstcontact 448 positioned at a first via 449 and electrically connectedbetween one of the junctions 460 (e.g., to the first metal layer 454 cof the third junction 460 c), and to the second semiconductor material208. The electrostatic discharge device 450 additionally includes asecond contact 446 positioned at a second via 440 extending through theelectrostatic discharge device 450. The second contact 446 electricallycouples a junction 460 (e.g., the second metal layer 458 a of the firstjunction 460 a) to the reflective material 220 or, in furtherembodiments, to a separate conductive layer or to the firstsemiconductor material 204. The substrate 230 can be conductive so as toroute current to the second contact 446. An insulating material 461electrically isolates the first and second contacts 446, 448 fromadjacent structures.

In some embodiments, components of the electrostatic discharge device450 are deposited on the SSE 202 by PVD, ALD, plating, or othertechniques known in the semiconductor fabrication arts. The first andsecond vias 449 and 440 can be formed in the electrostatic dischargedevice 450 and/or the SSE 202 using the methods described above withreference to FIG. 3E. In a representative embodiment, the electrostaticdischarge device 450 is formed on the SSE 202 before the substrate 230is attached. In some embodiments, the electrostatic discharge device 450can be attached to the substrate and/or the SSE 202 by means of bondinglayers. In still further embodiments, the electrostatic discharge device450 can be positioned on a portion of an external surface of the SSE 202without the substrate 230.

FIGS. 5A and 5B are cross-sectional views of the SST device 400 of FIG.4 during operation in accordance with embodiments of the technology.During normal operation, as illustrated in FIG. 5A, current flows in thedirection of the arrows from the second contact 446 to the firstsemiconductor material 204, through the SSE 202 to the secondsemiconductor material 208 as described above, to the first contact 448.As illustrated in FIG. 5B, during an electrostatic discharge event, theSST device 400 can be protected from reverse currents by providing apath for reverse current flow, illustrated by the arrows, through thejunctions 460. The reverse current can be directed through the substrate230, rather than through the SSE 202.

FIG. 6 is a partially schematic, partial cross-sectional illustration ofa system 600 that includes a solid state emitter 202 having componentsgenerally similar to those described above, including an active region206 positioned between a first semiconductor material 204 and a secondsemiconductor material 208. The SSE 202 is carried by a supportsubstrate 230, and a conductive/reflective material reflects emittedradiation outwardly through the second semiconductor material 208. Thesupport substrate 230 can be conductive and can accordingly function asa first contact 646. The SSE 202 receives power from the first contact646 and a second contact 648.

The system 600 can further include a state device 695 that in turnincludes a photosensor 650 (e.g., a photodiode). The photosensor 650 canbe formed using residual material from the buffer layer 216 and theepitaxial growth substrate 210, in a manner generally similar to thatdescribed above with reference to FIGS. 2B-3D. In a particular aspect ofan embodiment shown in FIG. 6, the epitaxial growth substrate 210 isdoped and/or otherwise treated to form a photosensitive state-sensingcomponent 611. Representative materials for forming the state-sensingcomponent 611 include silicon germanium, gallium arsenide and leadsulfide. The state-sensing component 611 can be coupled to a first statedevice contact 651 and a second state device contact 652, which are inturn connected to the controller 280. An insulating material 653provides electrical insulation between the photosensor 650 and thesecond contact 648. In a further particular aspect of this embodiment,the buffer layer 216 is transparent, allowing light emitted from theactive region 206 to impinge upon the state-sensing component 611. Thisin turn can activate the state-sensing component 611, which in turntransmits a signal to the controller 280. Based upon the signal receivedfrom the state device 695, the controller can direct the power source270 to supply, halt, and/or change the power provided to the SSE 202.For example, if the state device 695 identifies a low output level forthe SSE 202, the controller 280 can increase the power provided to theSSE 202. If the SSE 202 produces more than enough light, the controller280 can reduce the power supplied to the SSE 202. If the color, warmth,and/or other characteristic of the light detected by the state device695 falls outside a target range, the controller 280 can control thepower provided to the SSE 202 and/or can vary the power provided tomultiple SSEs 202 that together produce a particular light output.

FIG. 7 is a partially schematic, partial cross-sectional illustration ofa device 700 that includes a state device 795 in the form of aphotosensor 750 in accordance with another embodiment. Unlike thearrangement described above with reference to FIG. 6, the photosensor750 shown in FIG. 7 is not formed from residual material used to formthe SSE 202. Instead, the photosensor 750 can include a state-sensingcomponent 711 and an electrically conductive, transparent material 712(e.g., zinc oxide) disposed between the state-sensing component 711 andthe second semiconductor material 208. The state-sensing component 711can include amorphous silicon and/or another material that is responsiveto light emanating from the active region 206 and passing through theconductive/transparent material 712. The state device 795 can furtherinclude first and second state device contacts 751, 752 that transmitsignals to the controller 280 corresponding to the amount, qualityand/or other characteristic of the light received from the active region206. An insulating material 753 provides electrical insulation betweenthe state device 795 and the second contact 648. Accordingly, the system700 (and in particular, the controller 280) can direct the operation ofthe SSE 202 based upon information received from the state device 795.

In both of the embodiments described above with reference to FIGS. 6 and7, the state device and state-sensing component are positioned so as toreceive at least some of the light that would normally be transmitteddirectly out of the solid state transducer. In particular, thestate-sensing devices can be positioned along a line of sight or opticalaxis between the active region 206 and the external environment thatreceives light from the active region 206. In other embodiments, thestate-sensing device can be buried within or beneath the SSE 202 of theoptical axis in a manner that can reduce or eliminate the potentialinterference of the state-sensing devices with light or other radiationemitted by the SSE 202. FIGS. 8A-8L describe a process for forming suchdevices in accordance with particular embodiments of the disclosedtechnology.

FIG. 8A illustrates a device 800 during a particular phase ofmanufacture at which the device 800 includes components generallysimilar to those described above with reference to FIG. 3A. Accordingly,the system can include an epitaxial growth substrate 210 upon which abuffer layer 216 and an SSE 202 are fabricated. The SSE 202 can includean active region 206 positioned between first and second semiconductormaterials 204, 208. A conductive, reflective material 220 is positionedto reflect incident light away from these first semiconductor material204 and through the active region 206 and the second semiconductormaterial 208.

The processes described below with reference to FIGS. 8B-8L includedisposing and removing material using any of a variety of suitabletechniques, including PVD or CVD (for deposition) and masking/etchingfor removal. Using these techniques, sequential layers of material arestacked along a common axis to produce the final product. Beginning withFIG. 8B, a recess 801 is formed in the conductive, reflective material220. The recess 801 allows light to pass from the SSE 202 to aphotosensitive state device formed in and/or in optical communicationwith the recess 801. In FIG. 8C, a transparent insulating material 802is disposed in the recess 801. In FIG. 8D, a transparent conductivematerial 712 is disposed on the transparent insulating material 802within the recess 801. As shown in FIG. 8E, a portion of the transparentconductive material 712 is removed, and the space formerly occupied bythe removed portion is filled with additional transparent insulatingmaterial 802. Accordingly, the transparent conductive material 712 iselectrically isolated from the surrounding conductive reflectivematerial 220 by the transparent insulating material 802.

In FIG. 8F, an additional layer of transparent insulating material 802is disposed over the transparent conductive material 712. In FIG. 8G, aportion of the transparent insulating material 802 positioned over thetransparent conductive material 712 is removed and replaced with astate-sensing component 811. In a representative embodiment, thestate-sensing component 811 include amorphous silicon, and in otherembodiments, the state-sensing component 811 can include othermaterials. In any of these embodiments, an additional volume oftransparent insulating material 802 is disposed on one side of thestate-sensing component 811, and a first contact material 803 isdisposed on the other side so as to contact the transparent conductivematerial 712.

In FIG. 8H, yet a further layer of transparent insulating material 802is disposed on the underlying structures. A portion of this layer isremoved and filled with additional first contact material 803 to form anelectrical contact with one side of the state-sensing component 811 viathe transparent conductive material 712. A second contact material 804is disposed in contact with the opposite surface of the state-sensingcomponent 811 to provide for a complete circuit.

In FIG. 8I, a further layer of transparent insulating material 802 isdisposed over the first and second contact materials 803, 804, and asubstrate support 830 is attached to the insulating material 802. Thestructure is then inverted, as shown in FIG. 8J and the epitaxial growthsubstrate 210 and buffer material 216 shown in FIG. 8I are removed.Accordingly, the second semiconductor 208 material is now exposed. InFIG. 8K, a plurality of vias 840 (four are shown in FIG. 8K as vias 840a-840 d) are made through the substrate support 230 to an extentsufficient to make electrical contact with multiple components withinthe device 800. For example, a first via 840 a makes contact with thesecond semiconductor material 208 (or, as indicated in dashed lines, atransparent conductive layer overlying the second semiconductor material208), a second via 840 b makes contact with the conductive, reflectivematerial 220, a third via 840 c makes contact with the second contactmaterial 804, and a fourth via makes contact with the first contactmaterial 803. Each of the vias 840 a-840 d is lined with an insulatingmaterial 805 to prevent unwanted electrical contact with other elementsin the stack.

FIG. 8L is a partially schematic illustration of the device 800 aftereach of the vias 840 has been filled with a conductive material 806. Theconductive material 806 forms first and second contacts 846, 848, whichprovide power from the power source 270 to the SSE 202. The conductivematerial 806 also forms first and second state device contacts 851, 852that provide electrical communication with the controller 280. As in thecase of the embodiments described above with reference to FIGS. 6 and 7,the resulting state device 895 is stacked along a common axis with theSSE 202. Unlike the arrangement described above with reference to FIGS.6 and 7, the state device 895 (in the form of a photosensor 850) is notin the direct optical path of light or other radiation emitted by theSSE 202. In operation, the state-sensing component 811 receivesradiation through the transparent, insulating material 802 and thetransparent conductive material 712. Based upon the radiation incidenton the state-sensing component 811, the photosensor 850 can send asignal to the controller 280 which in turn controls the power source 270and the SSE 202.

Further details of particular embodiments for constructing an SST devicegenerally similar to that described above with reference to FIGS. 8A-8Lare included in co-pending U.S. application Ser. No. 13/218,289, titled“Vertical Solid State Transducers Having Backside Terminals andAssociated Systems and Methods”, filed on Aug. 25, 2011, andincorporated herein by reference. In other embodiments, the SST devicescan be coupled to external devices with contacts having positions,arrangements, and/or manufacturing methodologies different than thoseexpressly described above.

FIG. 9 is a partially schematic, partially exploded illustration of anSST device 900 that include a state device 995 configured to detectthermal characteristics associated with the SSE 202. In the illustratedembodiment, the state device 995 can include an insulating layer 902positioned between the conductive reflective contact 220 and astate-sensing component 911. In a further particular embodiment, thestate-sensing component 911 can include a thermistor material (e.g., asuitable polymer or ceramic) and in other embodiments, the state-sensingcomponent 911 can include other thermally sensitive materials (e.g.,resistive metals). In any of these embodiments, an additional volume ofinsulting material 902 can be positioned against the state-sensingcomponent 911 to “sandwich” the state-sensing component 911 andelectrically insulate the state-sensing component 911 from the SSE 202.First and second state device contacts 951, 952 provide electricalcommunication with the state-sensing component 911. In particularembodiments, the state-sensing component 911 can include a materialstrip with a serpentine shape that increases component sensitivity(e.g., increases impedance or resistance change as a function oftemperature). In other embodiments, the state-sensing component 911 canhave other shapes. The state device contacts 951, 952 and the SSEcontacts can have any of a variety of locations, including those shownin FIG. 9. For example, all the contacts can be located at the top ofthe device, or the state device contacts can be at the top of the deviceand one or more SSE contacts at the bottom of the device, or all thecontacts can be buried (e.g., as shown in FIG. 8L). These options applyto the ESD state-sensing components and optical state-sensing componentsdescribed above with reference to FIGS. 2B-8L as well.

In operation, the state-sensing component 911 can be coupled to acontroller generally similar to that described above with reference toFIG. 7, and can control the operation of the SSE in a manner based uponthermal inputs. In particular, the state-sensing component 911 can sensethe temperature of the SSE 202 and/or other components of the SST device900. In response to a high temperature indication, the controller canreduce the power provided to the SST device 900 to allow the SST device900 to cool before it becomes damaged. After the SST device 900 hascooled (an event also indicated by the state-sensing component 911), thecontroller can increase the power provided to the SST device 900. Anadvantage of the arrangement described above with reference to FIG. 9 isthat the state-sensing component 911 can provide feedback that reduceshigh temperature operation of the SSE 202. In particular, the feedbackcan be used to account for reduced SSE output, reduced safe drivecurrent, reduced forward voltage and/or reduced SSE lifetime, all ofwhich are associated with high temperature operation.

One feature of several of the embodiments described above is that thestate-sensing component can be formed so as to be integral with the SSTand/or the SSE. Embodiments of the integrally formed state devices arenot pre-formed structures and accordingly are not attachable to the SSTas a unit, or removable from the SST as a unit without damaging orrendering inoperable the SSE. The SSE and the state device canaccordingly be formed as a single chip or die, rather than being formedas two separate dies that may be electrically connected together in asingle package. For example, the SSE and the state device can both besupported by the same, single support substrate (e.g., the supportsubstrate 230). For example, they can be formed from a portion of thesame substrate on which the solid state emitter components are formed,as described above with reference to FIGS. 2-3G and 6. In theembodiments described with reference to FIGS. 4, 5, 7 and 8A-8L, thesame epitaxial growth substrate is not used for both the solid stateemitter and the state device, but the components that form the statedevice can be formed in situ on the solid state emitter. An advantage ofthe latter approach is that, in at least some embodiments, the statedevice can be formed so as to be on the side of the solid state emitteropposite from the path of light emitted by the solid state emitter.Accordingly, the presence of the state device does not interfere withthe ability of the solid state emitter to emit light or other radiation.

Although the state device can be formed integrally with the SSE or SST,it performs a function different than that of the SSE and, accordingly,includes materials different than those that form the SSE (e.g.,different than the first semiconductor material, the secondsemiconductor material, and the active region in between). This is thecase whether the same epitaxial growth substrate used for the solidstate emitter is used for the state device, or whether the state devicedoes not use the same epitaxial growth substrate. As a result, thematerials and structural arrangement of the state device are not limitedto the materials and structural arrangement of the SSE. This enhanceddegree of flexibility can allow for smaller state devices and greaterstate device efficiencies. For example, state devices in the form ofphotodiodes can include materials that are specifically selected to bethin and/or highly absorptive at the wavelength emitted by the SSE,producing a compact, efficient structure.

From the foregoing, it will be appreciated that specific embodiments ofthe technology have been described herein for purposes of illustration,but that various modifications may be made without deviating from thedisclosure. For example, some of the embodiments described above discussthe state devices as a diode (e.g., an ESD protection diode or aphotodiode). In other embodiments, the state device can include adifferent, non-linear circuit element. In still further embodiments, thestate device may be linear (e.g., the thermal sensor can be a linearthermal sensor). The electrostatic discharge device can be constructedand connected to protect the SSE from large reverse voltages, asdiscussed above in particular embodiments. In other embodiments, theelectrostatic discharge device can be connected with a forward bias toprevent the SSE from large forward voltages. In still furtherembodiments, the SSE can be connected to both types of ESDs, to protectagainst both high forward and high reverse voltages. Additionally, incertain embodiments, there may be more than one state devices for aparticular SST device. Furthermore, material choices for the SSE andsubstrates can vary in different embodiments of the disclosure.

Certain elements of one embodiment may be combined with otherembodiments, in addition to or in lieu of the elements of the otherembodiments, or may be eliminated. For example, in some embodiments, thedisclosed buffer material can be eliminated. In some embodiments, thebuffer material can be used to form the SSE, but not the state device.The disclosed state devices can be combined in other embodiments. Forexample, a single SST device can include any of a variety ofcombinations of ESD devices, photosensors and/or thermal sensors.Accordingly, the disclosure can encompass other embodiments notexpressly shown or described herein.

We claim:
 1. A solid state transducer system, comprising: a supportsubstrate having a first side and a second side; a solid state emittercarried by the support substrate over the first side of the supportsubstrate, the solid state emitter comprising a first semiconductorcomponent, a second semiconductor component, and an active regionbetween the first and second semiconductor components; a state devicecarried by the support substrate over the first side of the supportsubstrate and positioned to detect a state of the solid state emitter,wherein— the state device is formed from at least one state-sensingcomponent having a composition different than that of the firstsemiconductor component, the second semiconductor component, and theactive region, the state device and the solid state emitter are stackedalong a common axis, the state device includes a photosensor positionedto receive radiation emitted by the solid state emitter, and the signalcorresponds to a characteristic of the radiation; a first via extendingthrough the substrate to the first semiconductor component of the solidstate emitter, the first via having an electrically conductive materialthat defines a first emitter contact at the second side of thesubstrate; a second via extending through the substrate to the secondsemiconductor component of the solid state emitter, the second viahaving an electrically conductive material that defines a second emittercontact at the second side of the substrate; and a controlleroperatively coupled to the solid state emitter and the state device toreceive a signal from the state device and control the solid stateemitter based at least in part on the signal received from the statedevice.
 2. The system of claim 1, further comprising a power source, andwherein: the power source is electrically coupled to and provideselectric power to the solid state emitter, the characteristic of theradiation is a radiation output level, the controller is operativelycoupled to the power source and the controller is configured to increasethe power provided to the solid state emitter when the signal indicatesthat the radiation output level of the solid state emitter is below afirst level and decrease the power provided to the solid state emitterwhen the signal indicates that the radiation output level is above asecond level, and the second level is greater than the first level. 3.The system of claim 1, further comprising a power source, wherein thepower source is electrically coupled to and provides electric power tothe solid state emitter, wherein the controller is operatively coupledto the power source, and wherein the controller is configured to controlthe solid state emitter at least in part by controlling the power sourceto control the power provided to the solid state emitter.
 4. The systemof claim 1 wherein the solid state emitter, the state device, and thesupport substrate form a single die, and wherein the support substrateis the only support substrate of the die.
 5. The system of claim 1wherein the state device is formed from a plurality of materialsdisposed conformally and sequentially on the solid state emitter.
 6. Thesystem of claim 1, further comprising an external surface through whichradiation emitted by the active region passes, and wherein the statedevice is positioned off an optical axis between the active region andthe external surface.
 7. The system of claim 1, further comprising:first and second state device contacts connected to the state device,the first and second emitter contacts being addressable separately fromthe state device contacts.
 8. The system of claim 1, further comprising:a third via extending through the substrate and having an electricallyconductive material electrically coupled to the state device anddefining a first state device contact at the second side of thesubstrate; and a fourth via extending through the substrate and havingan electrically conductive material electrically coupled to the statedevice and defining a second state device contact at the second side ofthe substrate.
 9. A solid state transducer system, comprising: a supportsubstrate having a first side and a second side; a solid state emittercarried by the support substrate over the first side of the supportsubstrate, the solid state emitter comprising a first semiconductorcomponent, a second semiconductor component, and an active regionbetween the first and second semiconductor components; a state devicecarried by the support substrate over the first side of the supportsubstrate and positioned to detect a state of the solid state emitter,wherein the state device is formed from at least one state-sensingcomponent having a composition different than that of the firstsemiconductor component, the second semiconductor component, and theactive region, wherein the state device and the solid state emitter arestacked along a common axis, and wherein the state device includes aphotosensor; a reflective material positioned between the solid stateemitter and the photosensor to reflect radiation emitted by the solidstate emitter, wherein the reflective material includes an aperturepositioned between the active region and the photosensor to passradiation from the active region to the photosensor; a first viaextending through the substrate to the first semiconductor component ofthe solid state emitter, the first via having an electrically conductivematerial that defines a first emitter contact at the second side of thesubstrate; a second via extending through the substrate to the secondsemiconductor component of the solid state emitter, the second viahaving an electrically conductive material that defines a second emittercontact at the second side of the substrate; and a controlleroperatively coupled to the solid state emitter and the state device toreceive a signal from the state device and control the solid stateemitter based at least in part on the signal received from the statedevice.
 10. The system of claim 9 wherein the reflective material isconductive.